Hello, I have a white iPhone 4S 16Gb Unlocked (so I thought). I bought this phone for $649 from someone on Craigslist. Before you guys bash me for using Craigslist, here me out: I realize my mistake in using it and have learned my lesson. I bought it thinking I would be able to use my T-Mobile SIM card with it. I got home, opened the box, put my SIM in, and the phone went through the "Apple splash screen" and told me to set up the phone. ***THE PHONE GAVE A SIGNAL OF 1 (ONE) BAR, AND THAT IT WAS ON EDGE. Yet it never said "T-Mobile"*** All was going well until it told me at the end that my SIM card was not valid and to insert the SIM card from the carrier whom I bought it from. Not knowing what to do, I inserted my old AT&T SIM (currently has no service on it whatsoever) and the phone got past the set-up screens. Clueless, I went into Settings --> General --> About and looked at the model number. It reads "MD237LL." The carrier was "AT&T 11.0." I suspected this was because I had an AT&T SIM inserted. I then decided to take out the AT&T SIM and insert my T-Mobile. The phone went through the "Apple splash screen" once again and I ended up just like last time: One bar, edge network, but the SIM would not register. So I once again inserted the AT&T SIM and got through to the home screen. However, this time I turned on Airplane Mode and took out the AT&T SIM. I then inserted my T-Mobile SIM and turned off airplane mode. Sure enough, my phone registered with T-Mobile's network. It even told me I had one new voicemail. However there were ZERO (0) signal bars. I went into Settings --> General --> About and my carrier was "Carrier 11.0." Yet the phone was connected to Edge it said. WiFi was off. To test this, I tried making a phone call: the call would not go through. But I tried Siri and sure enough, Siri worked. Now I am stuck. What do I do? I've restored my phone to factory settings via iTunes. Yet this still happens. Please help me. Thanks!